I have a friend who is 6'-9.5" and around 350 lbs. He considered buying a Prius because he found it comfortable with better headroom than most cars. He ended up staying with his Jeep because of the amount of driving he does in the snow on unplowed roads and wanted to keep the four-wheel drive.
I'd rather have it high. That way, I don't need an SUV! Honda have really really low seats. Their front passenger seat is low, especially since most of their lineup don't have height adjustable passenger seats. Sitting next to my friend who's almost the same height as I am, I feel like my mother. I'm probably half a head shorter since his driver's seat is raised.
I'm 6'2, 220. I find the Prius seats to be very uncomfortable... so much to the point that I'm seriously considering my wife's offer to trade cars (she has an extremely fast, comfortable 04 Accord V6). There is virtually no lumbar support, the shoulder area is way too narrow, the depth of the seat part does not extemnd far enough to support the area behind my knees (as it should) AND the seat doesn't go far back enough... and I hate the fact that the steering wheel doesn't telescope. These are extreme shortcomings imo (pardon the pun). Then again, had the seats been perfect, the car would be perfect for me.. and there is no such thing as a perfect car, at least in my experience.